Q I care for the grounds at a retirement community that has been given a collection of orchids for its lounge area. They have asked me to care for them. I know nothing about orchids and, because the collection belonged to a loved one, I am nervous about keeping them alive. Help. — Chicago, Ill.
A Caring for orchids can be intimidating. Anything with a flower as exotic as they are, set atop a plain stem over a leaf or two should be difficult, but they are not.
Although there are orchids that can be grown in nearly all climates, collectors orchids are typically tropical or subtropical and can be separated into two basic categories: semi-terrestrial and epiphytic. Epiphytes are plants that grow upon another living plant, with roots that grow around the support plant and other roots aerial. These orchids are not parasites, though. They produce their own food through photosynthesis and collect moisture and nutrients through the humid air of their climate and from decomposing organic matter found on the plants they are living on. Some have cups or other pockets that hold rainwater and dropped leaves, etc. Semi-terrestrial plants thrive in a more soil-like situation, but typically live in spaces with very loose soils or accumulations of organic matter. Knowing their natural environment should give you some clues to their care.
In general, epiphytic orchids prefer to go dry between waterings. Semi-terrestrials generally prefer to have consistent moisture without having their roots sit in soggy conditions. Do not use softened water. High humidity is preferable for most, but in an indoor environment, that can be hard to achieve. Many growers keep pebble trays filled with water under the orchid pots. The water evaporates, creating higher humidity, and the pebbles keep the bottom of the pots out of the water.
Nearly all orchids prefer a daytime temperature between 75°F and 85°F and nighttime temperatures between 60°F and 65°F. Most prefer at least bright light without direct sun during the hot part of the afternoon. The leaves can provide a good indication of the amount of light they are receiving. If leaves are dark green, the plant is not receiving enough light; if the leaves are reddish green or very yellow with brown margins, the plant may be receiving too much light.
Many genus prefer high-nitrogen fertilizer applied monthly. Some others, such as Cymbidiums and Paphiopedlums, prefer high-nitrogen fertilizers monthly for six months and low-nitrogen fertilizers for the remaining six months. To avoid growing orchids in soil mix that is too dense, repot them before the medium breaks down, usually every two to three years, depending on genus. Most prefer medium to fine fir bark (not pine bark), as a growing medium.
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